1. Technical Field
The present invention relates to a liquid crystal device and an electronic apparatus.
2. Related Art
In recent years, the vertical alignment mode has been adopted as the mode of aligning liquid crystal in a liquid crystal device for use in a projector. However, since liquid crystal molecules are aligned vertically to surfaces of substrates in the vertical alignment mode, interactions between the liquid crystal molecules are weak in the azimuth direction in which the liquid crystal molecules are tilted when applying a voltage. Accordingly, when applying a voltage, the liquid crystal molecules are tilted in various directions due to a lateral electric field that occurs from an electrode edge. Also, since some liquid crystal molecules do not contribute to display depending on the azimuth (that is, liquid crystal molecules parallel with the transmission axis of any one of polarizing plates under the crossed nicols condition do not make a phase difference), there occurs a problem that the transmittance becomes lower than that in parallel alignment.
In order to prevent a lateral electric field from affecting the alignment, a method of making a pretilt angle on a pixel electrode requiring strong alignment control force smaller than that on a counter substrate so as to reduce light leakage has been disclosed in JP-A-10-161127. However, a substantial average tilt angle for preventing a lateral electric field from affecting the alignment is almost the same as a pretilt angle used under mass-production conditions so that little effect for improving the contrast is obtained. Also, alignment layers provided on the opposed surfaces of the two substrates are manufactured by oblique evaporation, and if a liquid crystal device is mass-produced, multiple expensive apparatuses such as vacuum deposition systems are required. Accordingly, a large initial investment must be made.
For this reason, a method of preventing a lateral electric field from causing an alignment failure in TN mode, which is one of the liquid crystal display modes, using a technique of forming an inorganic alignment layer on an active matrix substrate by oblique evaporation and forming an organic alignment layer on a counter substrate using a typical mass-production method such as printing or a coating process, has been disclosed in JP-A-2002-296597.
As for JP-A-2002-296597, it is possible to reduce equipment investment, since an alignment layer is manufactured on a counter substrate using a typical mass-production method such as printing or a coating process. However, it is difficult to tilt liquid crystal molecules from a completely vertical state by performing rubbing on polyimide for vertical alignment that can be used as a coating. For this reason, in direct-view medium and small-size liquid crystal devices and large-size liquid crystal devices, the azimuth in which liquid crystal molecules are tilted when a voltage is applied is determined using a lateral electric field caused around an edge of each pixel electrode or a protrusion (surface shape) provided on a surface of an electrode. As for this method, a disclination attributable to competition between liquid crystal molecules almost always occurs in each pixel; however, such a disclination is not remarkable, since the size of each pixel is several tens of micron meter. Nevertheless, a liquid crystal panel, such as HTPS (high temperature poly-silicon) or LCOS (liquid crystal on silicon), that is used as a light valve of a projector and whose pixel size is around 10 μm has a problem that a disclination can be visually recognized during projection so that display quality is degraded.